*
* Copyright (c) 2020 NVI, Inc.
*
* This file is part of VLBI Field System
* (see http://github.com/nvi-inc/fs).
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
      integer function ifirst_non_white(ldum)
      implicit none
! Find the first non  space or non-tab characer.
! History
!  2007Nov04 JMGipson.  First version

      character*(*) ldum
      integer i
      character*1 ltab
      ltab=char(9)    ! Tab character.

      do i=1,len(ldum)
        if(ldum(i:i) .ne. " ".and.ldum(i:i) .ne. ltab) then
           goto 100
        endif
      end do
100   continue
      ifirst_non_white=i
      return
      end
